The present disclosure relates to blood pumps for cardiac support. More particularly, the present disclosure relates to expandable blood pumps and methods of their deployment and use for circulatory support. A variety of cardiac problems result in the need for temporary cardiac support. These scenarios can range from contingency support during high risk cardiac surgery to immediate full support after a myocardial infarction. Acute pumps for temporary cardiac support differ from implantable pumps because the period of use may be measured short-term, in days or weeks, rather than long-term months or years. Situations requiring temporary cardiac support can benefit strongly from quick deployment of a blood pump in a range of anatomical locations.
The blood pumps of the present disclosure have application in different aspects of the cardiovascular system. The body's cardiovascular system is a closed loop system, which consists of two types of circulation, pulmonary circulation and systemic circulation. In pulmonary circulation, blood flows from the right portion of the heart through the pulmonary trunk, which branches into pulmonary arteries, which carry the blood flow to the lungs. In the lungs, blood flows through pulmonary capillaries, where carbon dioxide is removed from, and oxygen added to, the blood. The oxygenated blood then flows to the left portion of the heart, where it is pumped through the aorta to flow throughout the body. The pumping of oxygenated blood throughout the body is known as systemic circulation. In systemic circulation, the left side of the heart pumps blood through the aorta and into the arterial system, which carries the blood throughout the body, to capillaries, and to the body's cells. As the oxygenated blood flows through the body, the cells of the body remove the oxygen from the blood and replace it with carbon dioxide. The blood then enters the venous system, to begin its return trip to the heart and lungs. The venous system contains venules, which converge into veins. In the body's upper section, blood flows from the veins into the superior vena cava, while in the lower section of the body, the blood flows from the veins into the inferior vena cava. Blood flows from the superior vena cava and from the inferior vena cava into the right atrium of the right heart, where it reenters the cycle of pulmonary circulation.
Because blood flows from the right portion of the heart and into the lungs, while blood that flows from the left portion of the heart is circulated throughout the body, the left heart generates substantially higher pressure than the right heart. The pressure generated by the right heart would not be sufficient to move blood throughout the body's tissues, while the pressure generated by the left heart, if applied to blood that circulates through the lungs, would damage the fragile alveoli tissue in the lungs. In general, the right heart generates systolic pressures of 15-30 mm Hg and diastolic pressures of 3-8 mm Hg, while the left heart generates systolic pressures of 100-140 mm Hg and diastolic pressures of 3-12 mm Hg.
There exists a need in the art for blood pumps that can improve aspects of this type of therapy. More specifically, there is a need in the art for improved expandable blood pumps for cardiac support, and further, for cardiac support for the left portion of the heart, the right portion of the heart, or both.